formatUnsigned

    fn formatUnsigned(w: *Writer, ns: u96) Writer.Error!void {
        var ns_remaining = ns;
        inline for (.{
            .{ .ns = 365 * std.time.ns_per_day, .sep = 'y' },
            .{ .ns = std.time.ns_per_week, .sep = 'w' },
            .{ .ns = std.time.ns_per_day, .sep = 'd' },
            .{ .ns = std.time.ns_per_hour, .sep = 'h' },
            .{ .ns = std.time.ns_per_min, .sep = 'm' },
        }) |unit| {
            if (ns_remaining >= unit.ns) {
                const units = ns_remaining / unit.ns;
                try w.printInt(units, 10, .lower, .{});
                try w.writeByte(unit.sep);
                ns_remaining -= units * unit.ns;
                if (ns_remaining == 0) return;
            }
        }

        inline for (.{
            .{ .ns = std.time.ns_per_s, .sep = "s" },
            .{ .ns = std.time.ns_per_ms, .sep = "ms" },
            .{ .ns = std.time.ns_per_us, .sep = "us" },
        }) |unit| {
            const kunits = ns_remaining * 1000 / unit.ns;
            if (kunits >= 1000) {
                try w.printInt(kunits / 1000, 10, .lower, .{});
                const frac = kunits % 1000;
                if (frac > 0) {
                    // Write up to 3 decimal places
                    var decimal_buf = [_]u8{ '.', 0, 0, 0 };
                    var inner: Writer = .fixed(decimal_buf[1..]);
                    inner.printInt(frac, 10, .lower, .{ .fill = '0', .width = 3 }) catch unreachable;
                    var end: usize = 4;
                    while (end > 1) : (end -= 1) {
                        if (decimal_buf[end - 1] != '0') break;
                    }
                    try w.writeAll(decimal_buf[0..end]);
                }
                return w.writeAll(unit.sep);
            }
        }

        try w.printInt(ns_remaining, 10, .lower, .{});
        try w.writeAll("ns");
    }